DE1154441B - Voltage source for electrostatic precipitators - Google Patents

Description

The invention relates to a voltage source for electrostatic precipitators, which via a high-voltage transformer and a downstream high-voltage rectifier receive direct voltage potential. To ensure a high degree of dust removal achieve a number of requirements for the operation of an electrostatic precipitator. The high voltage should run up automatically after switching on until the desired current (nominal current) is reached in the separator. The system should continue to ensure that the voltage changes the separator impedance is at least approximately maintained. Occurs in the separator If the flashover occurs, the voltage should collapse until the arc is extinguished; afterward should the previous operating status automatically set itself again.

Attempts have been made in the design of controls for separators with great effort on aids such as relays etc. to meet the above requirements. This was a number of Sources of error are inevitable.

It is already known to use a Metadyne with short-circuited primary brushes as a voltage source for to use electrostatic precipitators. When using this voltage source, the voltage increases after switching on the load circuit slowly from zero to a certain value on automatically and remains approximately independent of fluctuations in the separator impedance constant; however, a major disadvantage is to be seen in the short-circuit behavior of the above voltage source, which is important for the operation of the separator. Kick namely a short circuit, d. H. if a flashover occurs, the voltage goes back to zero, but it remains however, get a certain short-circuit current. The above voltage source thus shows the known behavior a current-controlling transducer. With such a characteristic, however, is the automatic Arc quenching can be quite difficult. The relatively high short-circuit current also has a disruptive effect.

This disadvantage does not occur in the control for electrostatic precipitators according to the invention. According to the invention the high-voltage transformer and rectifier of the separator are connected on the low-voltage side connected to a capacitor-excited asynchronous generator. The generator can be two or more Have phases. A three-phase asynchronous generator is normally used, which is powered by a Three-phase asynchronous motor is driven.

The arrangement according to the invention ensures that the high voltage after the on

Voltage source
for electrostatic precipitators

Applicant:

Licentia Patent-Verwaltungs-G. mb H.,
Frankfurt / M., Theodor-Stern-Kai 1

Dr.-Ing. Otto Renner, Frankfurt / M.,
has been named as the inventor

switch automatically runs up until the desired current (nominal current) is set. If there is a change the separator impedance, this current is at least approximately maintained. Furthermore, the arrangement has without further ado, the effect that in the event of flashover in the separator the voltage up to extinction

as the arc collapses and then starts up again to the old operating state. Furthermore, it can be achieved in a simple manner that the Deposition voltage is automatically set to a selectable value of the flashover density, including the number the flashover in the separator per unit of time is to be understood.

To control the generator with regard to current and voltage, variable reactances are provided. For example, the excitation capacitors are variable. Preferably the generator is over controlled a variable inductance choke coil assembly. It is recommended to use direct current bias To use choke coils for this. Particularly favorable operating conditions are achieved by feedback of the generator voltage with the premagnetization.

An embodiment according to the invention is shown in Fig. 1 of the drawing. It is a three-phase asynchronous generator 2 drawn, which is driven by a three-phase asynchronous motor 1. The three-phase asynchronous generator feeds via the High-voltage transformer and the high-voltage rectifier 6 the electrostatic precipitator ?.

The capacitors 3 of a suitable size are placed at the output of the generator 2. The reactance the overall arrangement is through a

309 688/244

adjustable inductance changed. A star-connected transductor is provided, its inductance can be changed by the excitation winding 8. The one flowing through the excitation winding 8 Direct current can be set by the actuator 9, which is shown in the form of a variable resistor will. It is recommended that the voltage of the generator 2 z. B. via dry rectifier with the excitation winding 8 feed back.

The frequency of the generator 2 can be a multiple of the frequency of the motor 1. This will only a small type power of the capacitors 3 and the transducer 4 required; also increased thereby the control speed. The diversity of the frequencies is achieved through Choice of the appropriate number of pole pairs for the motor and generator.

In three-phase operation, all reactances such as capacitors 3 and inductors 4 can be switched either in star or delta.

The automatic setting of the separator voltage to a selectable value of the flashover density can be done using an arrangement as proposed in patent application L 32076 VIHc / 12e has been. In the exemplary embodiment, this automatic mechanism acts on the actuator 9.

The behavior of the voltage source according to the invention can be seen from the diagram according to FIG. This diagram shows in particular the favorable short-circuit behavior.

The dash-dotted line is the separator characteristic. The solid line is the current-voltage characteristic of the capacitor-excited asynchronous generator with a certain reactance, ie with a certain setting of the potentiometer 9 (FIG. 1). The intersection of the generator characteristics with the separator characteristic gives the operating values of the separator. Within the range / = 0 to / = Jcritical , the voltage at the generator output is practically independent of the current when the load changes, ie when there are fluctuations in the impedance. The Abscheiderstrom reaches the value J _k ritisch or values that are higher, ie occurs a flashover in the separator, so tilts the generator. Voltage and current tend to zero in a very short time, which means that in all cases standing arcing is automatically and reliably extinguished, even with high separator currents. Since the dumping time is very short, the rollover will also be quickly erased.

Claims (6)

PATENT CLAIMS: 1. Electrostatic precipitator system with a voltage source formed from an electrical generator, characterized in that a known capacitor-excited asynchronous generator is provided as the electrical generator, which is connected on the primary side to a high-voltage transformer feeding the electrostatic precipitator via a rectifier arrangement. ao 2. Plant according to claim 1, characterized in that that the asynchronous generator (2) is driven by an asynchronous motor (1). 3. Plant according to claim 1 or 2, characterized in that for setting the reactance value an adjustable inductance (4) is provided. 4. Plant according to claim 3, characterized in that a pre-magnetizable inductance (4) is provided, the excitation current of which is adjustable (excitation winding 8). 5. Plant according to claim 4, characterized in that the generator voltage with the excitation winding (8) the inductance is fed back. 6. Installation according to claim 1 or the following, characterized in that the frequency of the Asynchronous generator (2) is a multiple of the frequency of the asynchronous motor (1). Considered publications: German patents No. 694 764, 697 032,
142. 1 sheet of drawings θ 309 6M / 244 9.63